Today I received a sample of the O1 Headphone AMP/DAC from Fang at Head-Direct.com. It is a compact unit measuring approximately 4.5" wide, by 6" deep, and 2.5" of height.

The unit has three inputs on the back, these are:

- Optical Cable
- Coaxial Cable
- Two(2) RCA for analog inputs

The back also has the IEC power input and the On/Off switch. Overall it appears to be a well made and executed unit. Here are some pictures, please click on the thumbnail to view the full size picture.

The O1 Headphone AMP/DAC is renamed as the Octavart. You can read more about the $299 Octavart at: Head-Direct.com

I will be spending sometime w/ the O1 Headphone AMP/DAC over the next days and I hope to post my impressions. So far after about 20 minutes of playing I can say that I really like this unit. This unit would be perfect as an office rig, college student, or a den unit. At the moment I am feeding it Apple Lossless Files from my computer via the Chaintech AV710 sound Card and an optical cable.

The headphones in use are the AKG K701 and the Arturo Sandoval's Trumpet sounds very liquid and mellow. I am surprised I am using the word mellow describing Arturo's sound, he is a fantastic horn player but at times he goes wild and the music becomes a tad "metalic" sounding.

This is not the first I have heard of this unit since HiFlight owns one and he likes it a lot. However it is not an unit that many here own, as demonstrated by not finding any reviews or comments using the search function. Anyways I will continue listening and will post additional view and comments over the next couple of days.

I have spent the last two days listening exclusively to this amp/dac. My source continues to be the Apple Lossless files in my Dell Computer. I continue to use an optical cable from my Chaintech soundcard to feed the re-named Octavart and the cans are an AKG K701.

For such an inexpensive unit to have the instrument separation and placement, with such a level of detail borders on the un-real. I look forward to Mike's (tyrion) mini-meet this coming Saturday so that others listen to this unit and provide additional feedback.

The one area that is disconcerting is when the source starts sending its signal to the re-badged Octavart. During first few seconds you hear a clicking, at first I thought my Arcam's transport was damaged. Then I realized it was a switching noise for the Octavart in re-acquiring the signal (going from the optical to the coaxial).

I will post again in the next couple of days. Hope to use the AKG K501 and the RS-1 headphones for my next impressions.

The one area that is disconcerting is when the source starts sending its signal to the re-badged Octavart. During first few seconds you hear a clicking, at first I thought my Arcam's transport was damaged. Then I realized it was a switching noise for the Octavart in re-acquiring the signal (going from the optical to the coaxial).

I think that's normal. Both Lite DAC-60s I have owned did that when switching from coaxial to optical and back. I always thought it was a sign of high quality, very distinct audible feedback.

This is a very fine amp with digital input capability that should be seriously considered when searching for a desktop amp. It is a very accurate and clean-sounding amp. Headroom and dynamics are outstanding. Mucho power for inefficient phones.

This amp looks interesting...have you guys tried any Grado with the amp?

I tried the O1 with Audio Technica AD900's at Headphonic in Australia, as well as briefly at home as a loaner. The noise floor was too high for my liking, and I went with an Arietta instead. Most Grado models have similar sensitivity to the AD900, so it might not be the best choice.

The noise floor was pretty flat with volume though, so it wouldn't be a problem with less sensitive phones.

I tried the O1 with Audio Technica AD900's at Headphonic in Australia, as well as briefly at home as a loaner. The noise floor was too high for my liking, and I went with an Arietta instead. Most Grado models have similar sensitivity to the AD900, so it might not be the best choice.

The noise floor was pretty flat with volume though, so it wouldn't be a problem with less sensitive phones.

I have used it w/ the Grado RS-1 and have not heard the noise. Now Boomana has the amp, I look forward to her mpressions.

I have now had this amp (O1 DAC) for over 2 weeks, and it has been a joy to listen to. Really takes the veil away compared to the use of my main amp (Arcam 8se, which I thought gave a really good sound anyway). I have been so pleased with it, the current model is now part of my hifi. And have bought another one for the use of the computer. As I was considering using this amp for the computer and I’m now getting another one for the hifi. For a UK buyer, £150 or $299 it’s a real bargain. I will soon have a full review on this Amp.